Assessing and Managing Storm-Damaged Trees
Certain trees can be a beautiful part of a homeowner’s landscape, but with snow, ice and heavy winds, those same trees can become an eyesore and a safety hazard.
Following a storm, landowners should assess damage and decide whether to rehabilitate or remove a tree. The decision can sometimes be difficult, especially when the damaged tree is large, old or an heirloom.
“It’s often difficult to part with a large shade tree. Be realistic when making your decision,” said David Hillock, Oklahoma State University Extension consumer horticulturist. “As a general rule of thumb, if more than 50 percent of the tree crown has been damaged, the likelihood of survival is small.”
Ice storms have a knack for exposing pre-existing problems with trees. A frequent type of damage that greatly shortens a tree’s longevity occurs when large limbs break and peel bark down the trunk. This leaves a wound and opens the tree to infection by plant disease.
“Consider the long-term health of the tree and potential risk from leaving the tree in place,” Hillock said. “If you choose to save a severely damaged tree, you’ll need to commit to caring for that tree many years into the future.”
The first and most important step in pruning damaged trees is removing hazards such as hanging limbs, cracked branches and unstable trunks. However, improper care can create hazards in the future.
“Do not top trees. Topping, or dehorning, permanently ruins the structural integrity of the tree,” he said. “Topping will lead to adventitious growth, which is likely to break away from the tree during a future ice or windstorm.”
Not only will this have a negative impact on the structural integrity of the tree, it will also lose some visual appeal. Instead, broken limbs should be cut back to a branch that is at least one third the diameter of the branch being removed.
A branch should be cut just outside the branch collar, which is the swollen region where a branch connects to the trunk. Avoid cutting flush against the trunk, as this will create a wound that will not properly seal. Larger branches should be cut using the three-cut pruning method to avoid peeling bark. This process begins with the first cut about 6 inches to 12 inches out from the trunk on the underside of the branch, approximately a third of the way through. Next, cut through the branch just outside your first cut, leaving a stub on the tree. The final step is to make the pruning cut, leaving the branch collar on the trunk. Homeowners also may experience pine trees that have damaged leaders, which is the central shoot and top vertical branch of the tree. When the leader is broken, subsequent growth of the tree is altered.
“Without a leader, the pine will no longer grow upward, but rather spread outward,” Hillock said. “Sometimes we can try to establish a new leader.”
The first step in creating a new leader is to cut the broken shoot tip cleanly, just above a side branch. After attaching a sturdy stake to the tree trunk and allowing a section to extend beyond the broken tip, the largest lateral or side branch should be secured to the stake. This will direct the branch upward, and overtime, the lateral branch will become the new leader.
Oftentimes storm-damaged trees are too large for property owners to rehabilitate themselves. If that is the case, a professional arborist should be consulted. The Oklahoma Department of Agriculture, Food and Forestry provides an online list of certified arborists in its Forestry division.